The present invention relates to measurement of viscosity with a variable speed drive.
The state of the art of viscometry involves a calibrated application of shear force to a fluid to be tested and measuring torque and/or time-to-torque of the shear resistance of the fluid (its viscosity). See e.g., prior U.S. Pat. No. 3,886,789 (Jun. 3, 1975) of Donald W. Brookfield and U.S. Pat. No. 4,175,425 (Nov. 27, 1979) and U.S. Pat. No. 5167143 (Dec. 1, 1992) of David A. Brookfield, all of common assignment with the present application. See also, references cited in said prior patents.
It is an object of this invention to provide a reliable, but rugged instrument usable in quick change (test set ups) viscosity measuring applications, under pressurized and high temperature conditions.